JP2002186560A - Heat insulation container made of ceramic, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container made of a ceramic which has a vacuum hollow section, and of which the heat insulating property is excellent. SOLUTION: This heat insulation container made of the ceramic comprises an internal container 2 and an external container 3, and has a double structure wherein the vacuum hollow section 4 is provided between the internal container 2 and the external container 3. The internal container 2 and the external container 3 are formed of the ceramic of which the thickness is 1 to 3 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic container having a double structure which is used for mugs, cups, dishes, etc. and has a function of keeping foods such as tea, rice, ice cream and the like warm. is there.

[0002]

2. Description of the Related Art Conventionally, as a container for keeping and storing food and drink, a heat retaining container having a double structure such as a thermos made of metal such as stainless steel and a rice cooker has been widely used.

[0003] Such a heat retaining container is composed of an inner container and an outer container, and a vacuum hollow portion is formed between the inner container and the outer container, and acts as a heat insulating layer.

[0004] In the thermal insulation container, the inner container and the mouth of the outer container are joined to form a double container, a concave portion is provided on the bottom surface of the outer container, and an exhaust port is formed in a part of the concave portion. B ₂ O ₃ —PbO, B ₂ O ₃ having a softening point of 200 to 600 ° C. in the recess.
-Place a sealing material made of low-temperature molten glass such as ZnO,
After evacuating the hollow portion at a temperature lower than the softening point of the sealing material in a vacuum heating furnace the double container in which the sealing material is arranged,
It is manufactured by raising the temperature to a temperature higher than the softening point of the sealing material, softening the sealing material and sealing the exhaust port (Japanese Patent Laid-Open No.
No. 6-169850).

[0005] Further, a combination of an outer mold and a core is used, and a mold made of a material capable of absorbing a dispersion medium of ceramic slurry is used. There has been proposed a ceramic heat insulating container obtained by discharging a mud to obtain a double-structured ceramic molded body having a hollow portion and then firing the ceramic molded body (Japanese Patent Application Laid-Open No. Hei 8-309719).

[0006]

However, in a conventional metal heat insulating container, rust or discoloration occurs due to corrosion progressing from a joint surface of a mouth portion of an inner container and an outer container with a long-term use. However, because of its fertility, the smell is transferred to food and drink and the flavor is impaired.

In addition, a sealing material made of low-temperature molten glass such as B ₂ O ₃ —PbO, B ₂ O ₃ —ZnO is arranged in an exhaust port provided on the bottom surface of the outer container, and the sealing material is arranged. When evacuating the hollow part by baking the double container obtained in a vacuum heating furnace at a temperature lower than the softening point of the sealing material, lead (Pb), zinc (Zn), etc. contained in these sealing materials Gas is generated from the high vapor pressure element, and this gas causes the enlarging phenomenon of the encapsulant. The enlarging phenomenon causes the particle structure of the encapsulant to relax, thereby lowering the density and losing the hermeticity of the encapsulating part. In addition to the fact that the gas generated from the high vapor pressure element remains in the hollow portion and is sealed before being completely discharged, the hollow portion is not completely vacuumed and the heat retention is reduced. Had the disadvantage that

Further, the heat insulating container having a double structure made of ceramics has a drawback that the hollow portion is not vacuum, so that the food stored in the container has a low heat insulating property.

The present invention has been devised in view of the above-mentioned drawbacks, and has as its object to provide a ceramic heat insulating container having a vacuum hollow portion which has extremely high heat insulating properties and can be used for a long period of time. It is in.

[0010]

A ceramic heat insulating container according to the present invention comprises an inner container and an outer container, and has a double structure having a vacuum hollow portion between the inner container and the outer container. Wherein the inner container and the outer container are formed of ceramics having a thickness of 1 to 3 mm.

Further, the ceramic heat insulating container of the present invention comprises:
The surface roughness of at least the inner surface of the inner container and the outer surface of the outer container is 0.8 to 2.5 μm in arithmetic average roughness (Ra).

Further, a gypsum mold or a resin mold having a molding space and a casting hole is prepared, and a slurry made of a ceramic material is poured into the molding space from the casting hole to reach a predetermined thickness. After demolding, a ceramic molded body having a double structure consisting of an inner container, an outer container and a hollow portion was obtained, and after firing the ceramic molded body at a predetermined temperature, a sealing plug was inserted into an exhaust port located at the casting hole. And the melting point is 1200
A sealing material made of a glaze or a brazing material having a melting point of 850 ° C. or more is disposed, and then heated at a temperature of the melting point of the sealing material or more, and formed between the inner container and the outer container. The intermediate portion is evacuated and the exhaust port is sealed with a sealing plug fixed via a sealing material.

According to the ceramic heat insulating container of the present invention,
Because the inner container and outer container were made of ceramics,
Even when used for a long period of time, rust and discoloration do not occur, and fragrance and odor do not transfer to food and drink stored in the container, and the flavor of the food and drink can be improved.

The inner container and the outer container have a thickness of 1 to 3 m.
m, the inner surface of the inner container and the outer surface of the outer container have an arithmetic average roughness (Ra) of 0.8 to 2.5 μm, which is strong against impact and can be used for a long period of time. As a result, the sealing plug disposed at the exhaust port provided in the inner container or the outer container can be more firmly joined by the sealing material, so that the vacuum in the hollow portion is made higher and the heat insulating property is maintained for a long time. And the food and drink stored in the container can be kept warm for a long time.

Further, according to the production method of the present invention, a ceramic molded body having a double structure consisting of an inner container and an outer container can be easily obtained by casting, and further, a sealing plug and a melting point of 1200 are provided at the exhaust port. Glaze above ℃ or melting point 850 ℃
A sealing material made of the above brazing material is arranged and heated at a temperature equal to or higher than the melting point of the sealing material, and the intermediate portion formed between the inner container and the outer container is evacuated and the exhaust port is sealed. When sealing with a sealing plug through the material, the material is not heated to a low temperature at which gas is generated from the sealing material, thereby maintaining the hermeticity of the sealed part and extending the food and drink stored in the container. Can be kept warm over time.

[0016]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a perspective view showing one embodiment of the ceramic heat insulating container of the present invention, and FIG. 1B is a sectional view taken along line XX of FIG. 1A.

As shown in FIG. 1, the ceramic heat-insulating container of the present invention comprises a lid 1, an inner container 2 and an outer container 3, and a vacuum hollow portion between the inner container 2 and the outer container 3. 4 are provided.

The lid 1, the inner container 2, and the outer container 3 are made of ceramics such as an aluminum oxide sintered body and a zirconium oxide sintered body. For example, they are made of a zirconium oxide sintered body. In this case, zirconium oxide (ZrO ₂ ) powder is mixed with 30 to 40% by weight of aluminum oxide (Al ₂ O ₃ ) powder and ₂ % of cobalt oxide (CoO) powder.
0-30 wt%, the yttrium oxide (Y ₂ O ₃₎ powder 0.1 to 5% by weight, dispersant, organic solvent, and adding and mixing an organic solvent to obtain a mud漿物, then molded-the mud漿物A ceramic molded body having a predetermined shape is obtained by injecting through a casting hole of a casting mold and depositing, and the ceramic molded body is manufactured by firing at about 1400 ° C.

When the inner container 2 and the outer container 3 are formed of a zirconium oxide sintered body, the zirconium oxide sintered body has a small thermal conductivity of about 0.009 (W / m · K). It can hold the heat of foods and drinks stored in the thermal insulation container for a long time, and the food and drinks stored in the container do not transfer fragrance and odor, and as a thermal insulation container without impairing the flavor of the foods and drinks It can be suitably used.

When the inner container 2 and the outer container 3 are made of a zirconium oxide sintered body, if the average crystal particle diameter of zirconium oxide is 3 μm or less, the mechanical strength of the ceramic heat insulating container is increased. For a long period of time, more preferably 2 μm or less. If the open porosity is set to 1% or less, the mechanical strength of the ceramic heat-insulating container is increased to enable long-term use, and it is more preferable to set the porosity to 0.2% or less.

Further, the lid 1, inner container 2, and outer container 3
Has a thickness of 1 to 3 mm, whereby the mechanical strength of the heat retaining container is strong and the heat retaining effect can be sufficiently exhibited. The lid 1, the inner container 2, and the outer container 3 are
If the thickness is less than 1 mm, the vacuum hollow portion 4 cannot be held, and chipping or breakage is likely to occur. On the other hand, 3m
If it exceeds m, the thickness as a heat insulating container becomes large, which is not practical. Therefore, the thickness of the lid 1, the inner container 2, and the outer container 3 is specified in the range of 1 to 3 mm.

The lid 1, the inner container 2, and the outer container 3
Can be adjusted by controlling the inlay time during casting.

Further, the inner surface of the inner container 2 and the outer container 3
It is preferable that the outer surface has an arithmetic average roughness (Ra) of 0.8 to 2.5 μm. When the surface roughness is set to 0.8 to 2.5 μm in terms of arithmetic average roughness (Ra), a sealing plug arranged at an exhaust port provided on the bottom surface of the outer container 3 described later is further strengthened by a sealing material. Therefore, it is possible to increase the vacuum of the hollow portion 4 and maintain the heat insulating property for a long time, and to keep the food and drink stored in the container for a long time.

The surface roughness of the inner surface of the inner container 2 and the outer surface of the outer container 3 is calculated as an arithmetic average roughness (Ra) of 0.8 to 2.5.
In order to make μm, the surface roughness of the casting mold is controlled. Further, if the opening and the end face of the bottom surface of the ceramic heat insulating container composed of the inner container 2 and the outer container 3 are chamfered, the ceramic heat insulating container will not be damaged or chipped when an impact is applied. Can be prevented. Therefore, it is preferable to perform chamfering with a radius of curvature R of about 1 to 2 mm.

Next, the method for manufacturing the ceramic heat insulating container of the present invention will be described in detail.

As shown in FIG. 2A, a casting mold 5 made of gypsum, resin, or the like, has a molding space 6 therein corresponding to the shape of the heat retaining container, and is a vertically split mold. Prepare

A casting hole 7 into which a slurry is poured is opened in the bottom surface of the outer container 3 in the molding space 6.

Next, the molding space 6 is filled with a slurry made of a ceramic raw material through the casting hole 7.

As the ceramic raw material to be filled in the molding space 6, for example, a slurry obtained by adding a dispersant, an organic solvent, and an organic solvent to the above-mentioned zirconium oxide (ZrO ₂ ) powder and mixing them is used.

Further, the slurry made of the ceramic raw material is laid in a thickness of about 1 to 4 mm along the shape of the casting space 6 in several minutes to several tens of minutes, and after excess slurry is discharged,
As shown in FIG. 1B, the ceramic molded body 8 having a double structure is formed by releasing the mold. The ceramic molded body 8 is provided with an exhaust port 9 at a position corresponding to the casting hole 7 as shown in FIG.

Next, the ceramic molded body 8 is
After firing at 00 ° C., as shown in FIG.
Then, a sealing plug 10 made of the same ceramic and a sealing material 11 made of glaze having a melting point of about 1300 ° C. are arranged on the joint surface.

Thereafter, the container in which the sealing plug 10 and the sealing material 11 are arranged is fired in a vacuum heating furnace at a temperature of about 1300 to 1350 ° C., so that the hollow material is reached when the melting point of the sealing material 11 is reached. The air inside the part 4 expands, the firing is completed, and the hollow part 4 sealed with the sealing plug 10 is reduced in pressure by cooling to room temperature to be in a vacuum.

This can be explained by the well-known law of thermodynamics, that is, the so-called Boyle-Schart's law. After evacuation, the inside of the furnace is heated to a temperature higher than the melting point of the sealing material 11, the sealing material 11 is melted, and the sealing plug 10 is fixed and bonded.

In the above description, the sealing plug 10 disposed at the exhaust port 9 is replaced with the sealing material 1 made of glaze having a melting point of 1300 ° C.
After the ceramic molded body was fired, the exhaust port 9 was metallized with Mo-Mn, Ni, or the like, and the melting point was 85 in a vacuum atmosphere or an oxidizing atmosphere.
Sealing material 1 made of brazing material such as silver brazing or gold brazing at 0 ° C. or higher
After adhering and fixing by 1, firing and evacuation may be performed. In this case, the firing temperature of the sealing material 11 needs to be set to a temperature equal to or higher than the melting point of the brazing material (850 ° C.).

The melting point of the glaze or brazing material used as the sealing material 11 is 12 in the case of glaze.
It is preferable to use a material having a temperature of 00 ° C. or 850 ° C. or more in the case of a brazing material, and to fire at a temperature of the melting point or more. When bonding the sealing plug 10 with the sealing material 11,
If the sealing material 11 is baked at a temperature lower than the melting point, the sealing plug 10 cannot be bonded, and a gas containing impurities is generated from the sealing material, thereby reducing the risk of lowering the airtightness of the hollow portion 4. Have. Therefore, no gas is generated from the sealing material 11 by sealing with the sealing material 11 made of the glaze or brazing material having a high melting point, and the hermeticity of the sealed portion is maintained and the inside of the container is maintained. The stored food can be kept warm for a long time.

Further, the vacuum hollow portion 4 is formed in the same manner as described above.
To produce a lid 1 having a double structure. According to such a manufacturing method, it is possible to easily obtain a ceramic molded body having a double structure as a ceramic heat-insulating container, and to seal the exhaust port 9 with the sealing plug 10 via the sealing material 11. By firing, the hollow portion 4 can be easily evacuated, and a double-layer ceramic heat insulating container having the vacuum hollow portion 4 can be stably obtained.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Although the sealing material 11 was fired in a vacuum heating furnace for sintering, it may be fired in an oxidation heating furnace. In this case, too, the sealing material 11 was fired at a temperature equal to or higher than the melting point of the sealing material 11. By doing so, the hollow portion 4 is evacuated.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a heat insulating container having a double structure as shown in FIG. 1 was formed from a zirconium oxide sintered body, and an exhaust port formed on the bottom of the outer container was sealed with a zirconium oxide sintered body. The stopper is bonded and fixed with a sealing material made of glaze having a melting point of about 1300 ° C., baked at a temperature of 1300 to 1350 ° C., and then cooled to room temperature to evacuate the hollow to have a vacuum hollow. A sample of the thermal insulation container was manufactured.

In the same manner as described above, an inner container and an outer container made of a zirconium oxide sintered body are formed, and a sealing stopper made of a zirconium oxide sintered body is provided at an exhaust port with a melting point of about 900.
900 ° C. with a sealing material made of brazing material
After firing at a temperature of ９950 ° C., a sample having a vacuum hollow portion was manufactured by cooling to room temperature.

Further, as a comparative example, a heat insulating container having a double structure as shown in FIG. 1 was formed from a zirconium oxide sintered body in the same manner as described above, and the exhaust port was not sealed with a sealing material and the hollow portion was evacuated. No sample was made.

Each of the heat-insulating container samples obtained as described above
Hot water at 0 ° C. was poured, and the temperatures of the hot water 30 minutes later were compared.

Table 1 shows the results.

[0044]

[Table 1]

As is clear from Table 1, in the case where the hollow portion was not vacuum (Sample No. 1), the water temperature after 30 minutes was 40 ° C.
In contrast, the sealing plug was evacuated using a sealing material made of glaze and the hollow part was evacuated (Sample No. 2), and the sealing part made of a brazing material was evacuated. (Sample No. 3) was found to have a 30% or more hot water temperature of 56 ° C. or higher and an improved heat retention of 20% or more.

[0046]

According to the ceramic heat insulating container of the present invention, since the inner container and the outer container are formed of ceramics, rust and discoloration occur even during long-term use,
Gold and smell do not transfer to the food and drink stored in the container,
The flavor of food and drink can be improved.

The inner container and the outer container have a thickness of 1 to 3 m.
m, the inner surface of the inner container and the outer surface of the outer container have an arithmetic average roughness (Ra) of 0.8 to 2.5 μm, which is strong against impact and can be used for a long period of time. As a result, the sealing plug disposed at the exhaust port provided in the inner container or the outer container can be more firmly joined by the sealing material, so that the vacuum in the hollow portion is made higher and the heat insulating property is maintained for a long time. And the food and drink stored in the container can be kept warm for a long time.

Further, according to the manufacturing method of the present invention, a ceramic molded body having a double structure consisting of an inner container and an outer container can be easily obtained by casting, and further, a sealing plug and a melting point of 1200 are provided at the exhaust port. Glaze above ℃ or melting point 850 ℃
A sealing material made of the above brazing material is arranged and heated at a temperature equal to or higher than the melting point of the sealing material, and the intermediate portion formed between the inner container and the outer container is evacuated and the exhaust port is sealed. When sealing with a sealing plug through the material, the material is not heated to a low temperature at which gas is generated from the sealing material, thereby maintaining the hermeticity of the sealed part and extending the food and drink stored in the container. Can be kept warm over time.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing an embodiment of a ceramic heat insulating container of the present invention, and FIG. 1 (b) is an X- view of FIG. 1 (a).
It is sectional drawing in an X-ray.

FIGS. 2A to 2D are schematic diagrams illustrating a method for manufacturing a ceramic heat insulating container of the present invention.

[Explanation of symbols]

 1: lid 2: inner container 3: outer container 4: hollow part 5: casting mold 6: molding space 7: casting hole 8: ceramic molding 9: exhaust port 10: sealing plug 11: sealing material

Claims (3)

[Claims] 1. A heat insulating container having a double structure comprising an inner container and an outer container, and having a vacuum hollow portion between the inner container and the outer container, wherein the inner container and the outer container are thick. Is 1-3 mm
A ceramic heat insulating container characterized by being formed of ceramics. 2. An arithmetic mean roughness (Ra) of at least the inner surface of the inner container and the outer surface of the outer container of 0.8 to 0.8.
2. The ceramic heat-insulating container according to claim 1, wherein the thickness is 2.5 μm. 3. A casting gypsum mold or a resin mold having a molding space and a casting hole is prepared, and a slurry made of a ceramic material is poured into the molding space from the casting hole to reach a predetermined thickness. After demolding, a ceramic molded body having a double structure consisting of an inner container, an outer container and a hollow portion was obtained, and after firing the ceramic molded body at a predetermined temperature, a sealing plug was inserted into an exhaust port located at the casting hole. And a sealing material made of a glaze having a melting point of 1200 ° C. or more or a brazing material having a melting point of 850 ° C. or more. The intermediate portion formed therebetween is evacuated, and the exhaust port is sealed with a sealing stopper fixed via a sealing material.
The method for producing a ceramic heat-insulating container according to the above.